This invention relates to improved power actuated back rest assemblies for supporting a person's back and head while in a reclining or semi-reclining position.
Power actuated back rests of various types have been utilized in the past in adjustable beds, such as for example those used in hospitals. One such adjustable bed is shown in Donaldson U.S. Pat. No. 2,988,758 which teaches the use of a relatively bulky and indirect dual motor arrangement for the purpose. The two motors are located at the foot of the bed and actuate the head portion of the bed upwardly and downwardly by two drive mechanisms extending from the motors along opposite sides of the bed. Another prior art adjustable bed, which is on the market but not shown in any particular patent of which I am aware, incorporates an electro-hydraulic power unit, in which a motor drives a fluid pump which in turn actuates an hydraulic piston and cylinder arrangement located behind the head portion of the bed. Necessary parts include a high pressure fluid pump, reservoir, lines, piston and cylinder mechanisms, seals, solenoid valves, and rectifiers for the valves.
These and other prior art adjustable bed structures of which I am aware have had at least two major drawbacks in use. In the first place, their structure has been unnecessarily complicated and therefore more costly than would be desired, both as to initial investment and as to cost of repair. Further, these prior mechanisms are not adapted for supporting a person's back in many of the non-hospital situations in which an adjustable back rest might otherwise be desirable, as for instance on a sofa, or on a conventional mattress, or other supporting surface which is not part of an adjustable bed but on which a person may wish to lie at a particular time. The incorporation of each of the previously proposed powered back rest arrangements into a certain bed structure limits its versatility and prevents use of the back rest except on that particular bed.